Composites of webs, such as films and fibrous webs are used in absorbent articles. For example, nonwoven webs are often combined with polymer films such that they are useful as materials in absorbent articles, such as backsheets on disposable absorbent diapers. In such composites the nonwoven portion can provide softness while the film portion can provide for fluid impermeability.
Composites in which nonwoven fibers protrude through a polymer film can be useful for providing an absorbent structure in which the nonwoven acts as the conveyor of fluid from one side of the polymer film to the other. The composite can be structured such that the fluid collecting side of the composite is the polymer film and nonwoven fibers protrude through the polymer film to the fluid collecting side of the composite. For example, in a sanitary napkin or diaper, such a composite can be practical for use as a topsheet that transports fluid from the body facing surface of the sanitary napkin more deeply into the sanitary napkin towards the absorbent core. If a composite is used in an absorbent article, such as a sanitary napkin, diaper, or tampon, this may result in the retained fluid appearing as a stain on the body facing surface of the composite. Stains of menses, vaginal discharge, urine, and feces may not be viewed favorably by the wearer of the absorbent article.
Colored regions have been used to help mask absorbed bodily fluid, for instance menses or urine, collected by absorbent articles. The ability to mask the absorbed bodily fluids provides a wearer with an increased feeling of cleanliness and protection from soiled undergarments. Further, a colored region positioned in a secondary layer of the central region of an absorbent article, provides a desired visual impression of depth to a wearer. This perception of absorbent article depth increases a wearer's confidence in the absorption capacity of the absorbent article, resulting in increased confidence that bodily fluids will be successfully absorbed and stored; thereby reducing the chance of soiled undergarments.
However it has been difficult to produce absorbent articles having the desired colored regions. One of the difficulties has been providing the central region of an absorbent article with a colored region that will provide the desired coverage; as some wearers associate stain patterns that extend outside the central colored region as indicating that the absorbent capacity of the absorbent article is exhausted. In some absorbent articles, the central colored region could account for less than 25% of the absorbent capacity of the absorbent article. Most digital printers lack the width-wise spray area to provide the desired colored region width to the central region, especially if products are produced multi-lane or broad front, where two or more products are simultaneously on the production line. One attempted fix has been to try and arrange multiple digital printers in a side-by-side arrangement to provide increased spray area in the widthwise direction of the absorbent article. The rearrangement of the digital printers has not provided the desired results. The side-by-side arrangement increases the cost of the digital printers and further decreases the reliability of the printing process. If one of the coupled printheads in the width direction fails, the production line stops. Image quality is also at risk as the multiple digital printers must be coordinated to produce a colored region that is not noticeably offset in the machine direction. As the colored region is on or close to the absorbent article surface any errors are quickly noticed by a wearer, reducing or eliminating the benefits provided by colored regions.
Another attempt to provide colored regions having the desired coverage area has been to use a contact method of printing, such as flexographic printing. Contact printing has traditionally been an economical way to print large or wide patterns on an absorbent article with reproducible results. However, contact printing may result in higher initial expense because the specific pattern rolls, plates, or screens must be manufactured. Because of the custom manufacturing, subsequent changes to the print pattern may require the manufacture of new equipment and may limit the economic feasibility of quickly changing the print pattern for specific needs or limited production situations. A further issue is that contact printing does not work equally well with all substrates. For example, to create the visual perception of depth the central portion will be printed on to create a central colored region. However to create the visual perception of depth, a layer below the surface layer (top layer) is printed to produce the central colored region. In general the layers below the surface layer include “dusty” or “loose” non-woven or cellulose containing web materials that cannot be printed on using a contact method, as the loose fiber sticks to the print plate resulting in light or missing print.
In a further effort to provide the desired colored regions to an absorbent article, multiple printing processes have been used during the production of an absorbent article. These multiple printing processes have several shortcomings. In one method a single layer is printed on multiple times. However, printing on a single layer of an absorbent article multiple times does not provide a perception of depth that printing on multiple layers does. Another method involves printing on multiple layers of an absorbent article after they have been brought in contact with one another. This reduces the surfaces which can be printed, restricting printed webs to being in contact with one another, thus the perception of depth is lost. An additional method uses preprinted rolls of materials to produce absorbent articles. However the use of preprinted rolls increases the cost of the absorbent articles due to supply chain complexity and increased product scrap linked to registration of the image(s) in the preprinted roll.
Therefore there is a need for a method of producing absorbent articles having colored regions on multiple layers, one of which is a composite layer, such that the colored regions provide a visual perception of depth and sufficient coverage to at least partially mask absorbed bodily fluids.